Cryo-electron tomography of intact cells is likely to provide a global context to unify all structural data from crystallography/NMR and single molecule approaches, making it possible to determine the spatial arrangements of key proteins and complexes in the cell, with the exciting prospect of being able to follow spatial and temporal changes in these distributions during signaling events288. Despite the acknowledged immense potential of this methodology, several limitations have hindered its broader application in cellular and structural biology up to now. First, the thickness of cells, mammalian cells in particular (>1 um), limits the amount of useful information that can be recovered from whole cell tomograms;second, cellular tomograms contain an overabundance of information (interiors of cells are crowded), which often renders interpretation of densities within the tomographic volume and delineation of the spatial arrangement of the interesting molecules difficult;and third, given the nature of low dose imaging in which radiation damage to the biological specimen needs to be minimized, the locale of the region of interest is generally not known prior to data acquisition. We propose the following specific aims to develop and implement tools for cryo-electron tomography to overcome these technological barriers and enable cryo-electron tomography as a standard technology for examining HIV-host cell interactions.